Use of Exogenous and Endogenous Photomediators as Efficient ROS Modulation Tools: Results and Perspectives for Therapeutic Purposes

Abstract

Reactive Oxygen Species (ROS) play an essential dual role in living systems. Healthy levels of ROS modulate several signaling pathways, but at the same time, when they exceed normal physiological amounts, they work in the opposite direction, playing pivotal functions in the pathophysiology of multiple severe medical conditions (i.e., cancer, diabetes, neurodegenerative and cardiovascular diseases, and aging). Therefore, the research for methods to detect their levels via light-sensitive fluorescent probes has been extensively studied over the years. However, this is not the only link between light and ROS. In fact, the modulation of ROS mediated by light has been exploited already for a long time. In this review, we report the state of the art, as well as recent developments, in the field of photostimulation of oxidative stress, from photobiomodulation (PBM) mediated by naturally expressed light-sensitive proteins to the most recent optogenetic approaches, and finally, we describe the main methods of exogenous stimulation, in particular highlighting the new insights based on optically driven ROS modulation mediated by polymeric materials.

Untangling Photofaradaic and Photocapacitive Effects in Organic Optoelectronic Stimulation Devices

“…Upon illumination in physiological solutions, P3HT thin films or colloidal particles have been demonstrated to photochemically reduce oxygen to produce ROS, ultimately yielding H 2 O 2 as a metastable and easily quantifiable product. The ROS generation by P3HT has been exploited by Antognazza et al to yield light-induced physiological effects in both in vitro (Moros et al, 2018;Antognazza et al, 2019;Lodola et al, 2019) and in vivo models (Tortiglione et al, 2017). When evaluated by UV-V is spectroscopy, P3HT throughout these experiments affords a negligible drop in solid-state absorbance, suggesting that the P3HT is stable under these conditions.…”

Tuning photoelectrochemical performance of poly(3-hexylthiophene) electrodes via surface structuring

“…This especially applies for the growing applications of organic semiconductor photoelectrode biointerfaces for photostimulation of excitable tissues 7,8 and modulating cellular physiology. [9][10][11][12] In this work, we endeavor to nano/microstructure the surface of the bestknown example material in the aforementioned studies: poly(3hexylthiophene), P3HT. P3HT was employed widely in organic photovoltaics, 13 organic thin film transistors, and increasingly in bioelectronics applications.…”

“…8 P3HT can also generate photoelectrochemical currents, driving faradaic reactions and altering the (electro)physiology of cells. 19,20 Photoinduced physiological effects mediated by P3HT have been observed in a number of in vitro 8,10,11 and in vivo 21,22 models. P3HT can be conveniently coated from solution onto arbitrary substrates, but is also useful as an aqueous dispersion of nanoparticles.…”

“…26 The effects of photogenerated reactive oxygen species is an area of substantial interest in biophysics. 11,27 On the other hand, the possibility of hydrogen evolution via proton reduction on P3HT has been found to be very inefficient (in the absence of a cocatalyst) and occurs only in trace amounts compared to the dominant oxygen reduction reaction. 25,28 Herein, we have addressed the question of structuring P3HT for the purpose of tuning and enhancing its photoelectrochemical properties, and trying to understand the factors at play.…”

Organic thin film photofaradaic pixels for on-demand electrochemistry in physiological conditions

“…The use of organic semiconducting nanoparticles as light absorbers to photogenerate ROS has already begun to gain traction in biophysical research. [6][7][8] In our own research we have introduced aqueous organic dyes for photochemical ROS generation. 9 The aim of this work is to develop a solid-state photofaradaic device which can produce H 2 O 2 via O 2 reduction, while consuming sacrificial electron donors available in physiological conditions.…”